Despite what some other "for fun in normals" guides might say, Shaco is viable in ranked and a solid pick, particularly against melee supports and jungles.
In season 4, I played Morgana support and everyone said it was garbage and troll. Back then Morgana was considered a mid laner, but was in reality even stronger as a support than she is today. Then some high profile people started playing it and suddenly it was OP and had to be nerfed.
Just because something isn't popular, doesn't mean it's bad.

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I place 1-2 boxes for leash then be on time to place 2 boxes in the forward lane brush for cheese (this is still working in gold-plat games a lot. ) ( SEE VIDEO ABOVE )

first box in forward brush should drop when you hear "minions have spawned" , second as soon as cooldown allows.

When enemies come to lane, drop a box between them and turret about and inch and a half behind them and ignite, exhaust, go all-in.

Position yourself to body block escape and guide their pathing to boxes. ADC should poke minions inconspicuously at first.
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Alternatively, if you think cheese is not worth the risk, you can give an extra good leash on multiple camps. (2 boxes per camp on 2 camps)

After this initial phase, always drop a box somewhere in lane as soon as cooldowns allow, every time.
Keep at least 2 boxes at river entrance. if you are pushed up, keep a box several inches behind you, about 2/3 od the way between you and your turret. you will be maintaining 3-4 boxes at all times.

Against Evelynn, river boxes are not so important; place more boxes behind you.

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For dragons, prep the dragon area by placing boxes where the enemy would approach to contest. If you have advance notice, place multiple boxes.

Shaco support is strongest against enemy teams that have at least 2 or 3 melee champions.
If the enemy team has many squishy melees like yasuo/warwick, you almost win in champion select if you have any idea what's going on at all.

The more melees the enemy team has and the squishier they are, the more damage you can build, but going full AP has not been worth it in my experience.

In team fights against a more ranged team, boxes are still important, but being tanky and utilizing the slow from your passive will be a bigger factor. Protect yourself and a teammate with the face of the mountain active. With your clone you can soak up damage and slow 2 enemies at once, and when you've done all you can and your health is low, escape the fight with your Q.

Strong ADC's work well with Shaco. - Draven, Jinx, Jhin, Twitch, Tristana
Adc's that are not so good : Ezreal, Vayne

Unfortunately, many bot laners are unsure how the lane will play out and feel safe with an ADC like Ezreal. This for me has led to bad games. Weak ADC's can accomplish little with Shaco and require more patience than i have sometimes.
Therefore, I suggest dodging an Ezreal adc.

You can either start Ancient Coin or go with Relic start. Ancient coin will get you slightly more gold and i have been starting that recently.

For shoes, you have 3 choices as noted; recently i have been favoring the CDR shoes and the only reason to deviate from that is based on enemy team comp, but if you feel too squishy in the early game, do what you feel.

If i go with CDR shoes then i have been building randuin, as the CDR on warmog is wasted.
Warmog is a great item though, so if you go Tabi or mercs, probably build warmog after Censer and Zeke's

If you're not building Censer or Zeke's then you probably should not use these runes either, but i suggest one or both for pretty much every game.